JP2004109531A - Light quantity adjusting device and image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light quantity adjusting device and an image pickup device capable of realizing miniaturization. <P>SOLUTION: The slots 144a and 144b of diaphragm blades 14a and 14b with which driving pins 13a and 13b protrusively provided on a blade driving lever 12 are engaged are formed to be oblique to the acting direction of the blades 14a and 14b. The length of the slots 144a and 144b is extended, so that the stroke of the pins 13a and 13b is made longer. Since distances between the turning shaft 11a of a stepping motor 11 and the pins 13a and 13b are shortened, the light quantity adjusting device is miniaturized in a direction perpendicular to the actuating direction of the blades 14a and 14b. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light amount adjusting device having a step motor used for an optical device such as a digital still camera and a video camera, and an imaging device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a light amount adjusting device such as an optical device used for a digital still camera, a video camera, or the like, a device using a so-called galvanometer as a driving source has been widely used. In this aperture mechanism, the position of a rotor, which is a permanent magnet of a galvanometer, is detected using a Hall element, and the detection result is feedback-controlled, thereby operating the rotor to a target position and performing aperture control.
[0003]
However, when a galvanometer is used as a drive source for the aperture mechanism, a detection unit for detecting the position of the rotor is required, and a control unit for performing feedback control of an output result of the position detection unit is required. Therefore, there is a problem that the drive circuit becomes large, the substrate becomes large, and the number of components increases.
[0004]
Therefore, an aperture mechanism using a stepping motor instead of a galvanometer as a driving source is conceivable. In an aperture mechanism using a stepping motor, for example, a linear drive lever is press-fitted to a rotation shaft of the stepper motor, and drive pins are provided at both ends of the linear drive lever. The drive pins are respectively engaged with two aperture blades through vertical holes. In such an aperture mechanism, the stepping motor is rotated to cause the two aperture blades to move linearly in opposite directions. The light amount is adjusted by changing the size of the opening depending on the positional relationship between the two diaphragm blades.
[0005]
In the aperture mechanism using this stepping motor, means for detecting whether or not the aperture position is located at the initial position is required. For example, a home position detection means for detecting the initial position of the aperture is provided. (For example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-6-59309
[Problems to be solved by the invention]
In the light amount adjusting device using the above-described stepping motor, detecting means such as a home position detecting means for detecting whether or not the aperture position is located at the initial position and whether or not the stepping motor is out of synchronization is used. In addition, a circuit for driving this detection means is also required, which also causes a problem that the apparatus is increased in size and cost is increased.
[0008]
Further, in the light amount adjusting device using the above-described stepping motor, it is necessary to increase the moving amount of the aperture blade in order to increase the total aperture diameter. In order to increase the amount of movement of the aperture blade, if the rotation angle of the drive lever is fixed, the distance between the rotation axis of the drive lever and the drive pin must be increased, and the device becomes large in the direction perpendicular to the direction of movement of the aperture blade. There was a problem of becoming.
[0009]
The present invention has been made in view of such a problem, and an object of the present invention is to provide a light amount adjustment device and an imaging device that can realize miniaturization.
[0010]
[Means for Solving the Problems]
In the light amount adjusting device according to the present invention, the blade drive lever press-fitted to the rotating shaft of the stepping motor, the two drive pins protruding from the blade drive lever, and the long holes engage with the two drive pins, respectively. A light amount adjusting device for adjusting the amount of light passing through the opening by changing the area of an opening formed by linearly reciprocating the pair of diaphragm blades in opposite directions, comprising a pair of diaphragm blades, The long holes of the pair of aperture blades are formed oblique to the operating direction of the pair of aperture blades.
[0011]
In the light amount adjusting device according to the present invention, since the long holes of the pair of aperture blades are formed obliquely to the operation direction, the length of the long holes increases, and the stroke of the two drive pins increases.
[0012]
In the light amount adjusting device according to the present invention, the blade drive lever press-fitted to the rotating shaft of the stepping motor, the two drive pins protruding from the blade drive lever, and the long holes engage with the two drive pins, respectively. A light amount adjusting device for adjusting the amount of light passing through the opening by changing the area of an opening formed by linearly reciprocating the pair of diaphragm blades in opposite directions, comprising a pair of diaphragm blades, The stepping motor is driven from the fully open state of the opening to the fully closed state with the number of pulses corresponding to three pulses in the two-phase excitation. The energized state corresponding to the first pulse in the two-phase excitation and the second pulse in the two-phase excitation are applied to the stepping motor. Then, the initialization operation is performed by energizing to the energizing state corresponding to the 0th pulse in the two-phase excitation after energizing to the energizing state corresponding to.
[0013]
In the light quantity adjusting device according to the present invention, the initializing operation for setting the aperture position to the initial position can be performed only by controlling the energization of the stepping motor, so that it is not necessary to provide the initial position detecting means.
[0014]
An image pickup apparatus according to the present invention is an image pickup apparatus having a light amount adjusting device for adjusting a light amount, the light amount adjusting device includes a blade driving lever press-fitted to a rotating shaft of a stepping motor, and a protrusion protruding from the blade driving lever. An area of an opening formed by two provided drive pins and a pair of aperture blades each having a long hole engaged with each of the two drive pins, wherein the pair of aperture blades are linearly reciprocated in opposite directions. In the light amount adjusting device for adjusting the amount of light passing through the opening by changing the length of the aperture blades, the long holes of the pair of aperture blades are formed oblique to the operating direction of the pair of aperture blades.
[0015]
In the imaging device according to the present invention, the light amount can be adjusted by the light amount adjustment device that has been downsized, so that downsizing can be realized.
[0016]
An image pickup apparatus according to the present invention is an image pickup apparatus having a light amount adjusting device for adjusting a light amount, the light amount adjusting device includes a blade driving lever press-fitted to a rotating shaft of a stepping motor, and a protrusion protruding from the blade driving lever. An area of an opening formed by two provided drive pins and a pair of aperture blades each having a long hole engaged with each of the two drive pins, wherein the pair of aperture blades are linearly reciprocated in opposite directions. A light amount adjusting device that adjusts the amount of light passing through the opening by changing the number of pulses, the stepping motor being driven by a number of pulses corresponding to three pulses in two-phase excitation from a fully opened state to a fully closed state of the opening. Of the two-phase excitation, a current corresponding to the first pulse in the two-phase excitation and a current corresponding to the second pulse in the two-phase excitation are applied. And performs an initialization operation by energizing the energized state corresponding to the scan eyes.
[0017]
In the image pickup apparatus according to the present invention, the light amount can be adjusted by the downsized light amount adjusting device having no initial position detecting means, so that downsizing can be realized.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0019]
FIG. 1 shows a configuration of a light quantity adjusting device according to an embodiment of the present invention, and FIG. 2 shows a state of an aperture blade of the light quantity adjusting device shown in FIG. 1 in a fully opened state and a fully closed state. is there. FIG. 2A illustrates a state where the opening is fully opened, and FIG. 2B illustrates a state where the opening is fully closed. The light amount adjusting device 1 includes a stepping motor 11, a blade drive lever 12 rotated by the stepping motor 11, drive pins 13a and 13b protruding from both ends of the blade drive lever 12, and a drive pin 13a. , 13b are engaged with each other, and a cover metal plate 15 and a base 16 for accommodating and storing the pair of aperture blades 14a, 14b in the optical axis direction to restrict the movement of the pair of aperture blades 14a, 14b. The base 16 is provided with guides 16a and 16b for guiding the linear movement of the pair of aperture blades 14a and 14b.
[0020]
In the light amount adjusting device 1, the pair of aperture blades 14a and 14b linearly reciprocate in directions opposite to each other, so that the aperture 20 is formed by the aperture blades 14a and 14b. The amount of light is adjusted by changing the size of the aperture 20 depending on the positional relationship between the aperture blades 14a and 14b.
[0021]
The stepping motor 11 has a 90-degree electrical phase difference between a rotor having, for example, 10 poles magnetized alternately with S and N poles on a cylindrical outer peripheral surface, a rotating shaft 11a provided on the rotor, and a rotor magnet outer periphery. And two terminals 11b to 11e electrically connected to the two exciting coils. The stepping motor 11 is a two-phase stepping motor that rotates forward and backward by applying a frequency current having a phase difference of 90 degrees to two exciting coils by a stepping motor drive circuit.
[0022]
The stepping motor 11 is fixed to a stepping motor sheet metal 11f by welding, and the stepping motor sheet metal 11f is fastened to a stepping motor base 11g by screws 11h and 11i. Then, the stepping motor base 11g is attached to the base 16. The tip of the rotating shaft 11a of the stepping motor 11 is supported by a bearing of a stepping motor base 11g.
[0023]
The blade drive lever 12 has a through hole 12a into which the rotating shaft 11a of the stepping motor 11 is press-fitted, and a pair of arms 12b and 12c. Driving pins 13a and 13b are provided at ends of the pair of arms 12b and 12c, respectively. The pair of arms 12b and 12c are formed to open to the opening 20 side. The angle between the pair of arms 12b and 12c is not less than 90 degrees and less than 180 degrees, and has an angle of, for example, 125 degrees. Accordingly, in the operation direction of the aperture blades 14a, 14b, the area occupied by the aperture blades 14a, 14b when the opening 20 is fully closed can be reduced, and the light amount adjusting device can be downsized. Further, the light amount adjusting device can be downsized even in the direction perpendicular to the operation direction of the aperture blades 14a and 14b.
[0024]
The pair of aperture blades 14a and 14b are, for example, aperture portions 141a and 141b formed in a semicircular shape, horizontally long holes 142a and 142b inserted into a guide 16a projecting from the base 16, and projecting from the base 16. Elongated holes 143a, 143b inserted into the guide 16b, and drive pins 13a, 13b protruding from the blade drive lever 12.
And long holes 144a and 144b with which the holes 144a and 144b are engaged.
[0025]
The long holes 144a and 144b are formed obliquely to the operation direction of the aperture blades 14a and 14b. That is, the long holes 144a and 144b have an inclination of less than 90 degrees with respect to the operation direction of the aperture blades 14a and 14b, for example, have an angle of 54 degrees. The inclination of the elongated holes 144a and 144b is preferably 30 degrees or more with respect to the operation direction of the aperture blades 14a and 14b. If the inclination of the long holes 144a and 144b is not more than 30 degrees, a large frictional force is generated between the drive pins 13a and 13b and the long holes 144a and 144b, so that the aperture blades 14a and 14b may not move accurately. Because there is a nature.
[0026]
The guide blades 16a, 16b inserted in the horizontally long holes 142a, 142b and 143a, 143b guide the diaphragm blades 14a, 14b in a linear motion.
[0027]
The pair of aperture blades 14a and 14b, in which the horizontally long holes 142a and 142b and 143a and 143b are inserted through the guides 16a and 16b of the base 16, form a connection between the base 16 and the cover sheet metal 15 by attaching the cover sheet metal 15 to the base 16. It is stored in between.
[0028]
In order to adjust the light amount by the light amount adjusting device 1, the blade drive lever 12 is rotated forward and reverse by forward and reverse rotation of the stepping motor 11. The drive pins 13a, 13b protruding from the blade drive lever 12 are engaged with the elongated holes 144a, 144b formed obliquely to the operation direction of the aperture blades 14a, 14b. Slide horizontally in opposite directions. An aperture 20 is formed by the diaphragm portions 141a and 141b of the diaphragm blades 14a and 14b. The light amount passing through the opening 20 is adjusted by changing the area of the opening 20 depending on the positional relationship between the diaphragms 141a and 141b, and the light amount is adjusted.
[0029]
The blade drive lever 12 rotates 54 degrees corresponding to three pulses in two-phase excitation from the fully opened state of the opening 20 to the fully closed state. Further, for example, by performing micro-step driving by a sin-cos wave, the stepping motor 11 can be stopped at an arbitrary position, and the area of the opening 20 can be continuously changed.
[0030]
As described above, in the light amount adjusting device according to the present embodiment, the elongated holes 144a and 144b in which the drive pins 13a and 13b protruding from the blade drive lever 12 are engaged are connected to the aperture blades 14a and 14b. Are formed obliquely to the operation direction of the drive pins 13a and 13b, the lengths of the long holes 144a and 144b are increased, and the strokes of the drive pins 13a and 13b can be lengthened.
[0031]
Therefore, it is possible to increase the operation amount of the linear movement of the aperture blades 14a and 14b, and it is possible to increase the diameter of the opening 20. On the other hand, considering the case where the operation amount of the linear movement of the aperture blades 14a and 14b is constant, the distance between the rotation shaft 11a of the stepping motor 11 and the drive pins 13a and 13b can be shortened. It is possible to reduce the size of the light amount adjusting device in a direction perpendicular to the operation direction of 14b, and to narrow the rotation angle of the stepping motor 11.
[0032]
Further, in the light amount adjusting device according to the present embodiment, by adjusting the inclination of the long holes 144a and 144b with respect to the operation direction of the aperture blades 14a and 14b, the relationship between the rotation angle of the stepping motor 11 and the aperture value is adjusted. The desired relationship can be obtained.
[0033]
Next, with reference to FIG. 3, description will be given of an initialization operation for setting the aperture position to the initial position in the present embodiment. FIG. 3 shows the relationship between the energized state of the two phases A and B of the stepping motor 11 of the present embodiment and the rotation angle of the blade drive lever 12.
[0034]
To change the aperture by continuously changing the area of the opening 20 from the fully opened state of the opening 20 as shown in FIG. 2A to the fully closed state of the opening 20 as shown in FIG. From the energized state a (A phase = H, B phase = H) at which 20 is fully open, the energized state b (A phase = 0, B phase = H), energized state c (A phase = L, B phase = H) ), Energized state d (A phase = L, B phase = 0), energized state e (A phase = L, B phase = L), energized state f (A phase = 0, B phase = L), opening 20 The A-phase and B-phase energization states of the stepping motor 11 are continuously changed, for example, by microstep driving, to an energization state g (A phase = H, B phase = L) at which the motor is fully closed.
[0035]
In order to initialize the aperture position to the initial position, the stepping motor 11 is first energized, for example, for about 30 msec in the energized state c corresponding to the first pulse in two-phase excitation, for example. By this energization, if the blade drive lever 12 is located at the positions of the energized states a to e, the blade drive lever 12 rotates and is positioned at the energized state c. When the blade drive lever 12 is located at the position of the energized state f to g, the blade drive lever 12 does not operate and remains at that position.
[0036]
Next, the energization in the energization state e corresponding to the second pulse in the two-phase excitation is performed, for example, for about 30 msec for the stepping motor 11. With this energization, if the blade drive lever 12 is located at the position of the energized state c to g, the blade drive lever 12 rotates and is located at the position of the energized state e. That is, regardless of the position of the energized states a to g, the motor returns from the step-out state.
[0037]
Finally, the stepping motor 11 is continuously changed from energization in the energization state e to energization in the energization state a corresponding to the 0th pulse in two-phase excitation, for example. As a result, the blade drive lever 12 rotates, the opening 20 is fully opened, and the aperture position is at the initial position.
[0038]
As described above, in the light amount adjusting device according to the present embodiment, the initializing operation can be performed by performing the above-described energizing operation regardless of the position within the rotation allowable range of the stepping motor, and It is possible to omit the position detecting means of the stepping motor 11 or the blade drive lever 12 which is necessary for the above. Further, a circuit for driving the position detecting means is not required. Therefore, it is possible to reduce the size and cost of the light amount adjusting device.
[0039]
For example, the energization in the energization state e corresponding to the second pulse in the two-phase excitation is performed, for example, for about 30 msec, and thereafter, the energization in the energization state c corresponding to the first pulse in the two-phase excitation is performed, for example, for about 30 msec. Finally, for example, the current may be continuously changed to the energization in the energization state a corresponding to the 0th pulse in the two-phase excitation.
[0040]
When the initialization operation is performed in this manner, for example, in the digital still camera, the end is completely closed at the end of the energized state corresponding to, for example, the third pulse in the two-phase excitation. Since the normal operation is to energize the energized state corresponding to the 1st and 0th pulses to bring the opening 20 into the fully open state, the initialization operation can be performed by the normal operation.
[0041]
FIG. 4 illustrates an overall configuration of an imaging device including the above-described light amount adjusting device 1. In a photographing optical system of a camera as the image pickup apparatus 300, a field lens 301, a variable power lens 302, a light amount adjusting device 1, a focus lens 303, and a CCD image pickup element 304 are arranged from the object side. The lens frame 306 holding the variable power lens 302 and the lens frame 307 holding the focus lens 303 are guided linearly in the optical axis direction by a guide shaft (not shown). Note that the lens frames 306 and 307 have nut portions and are driven by lead screws of output shafts of the motors 308 and 309.
[0042]
The controller 310 calculates a pulse corresponding to the movement amount from the initial position to the target position, and transmits the calculation result to the stepping motor drive circuit 311 to drive the variable power lens 302 and the focus lens 303. The initial positions of the variable power lens 302 and the focus lens 303 are detected when the light blocking portions 306a and 307a of the lens frame enter between the light emission and light reception of the photo interrupters 312 and 313.
[0043]
In the stepping motor 11 of the light amount adjusting device 1, the coil is energized by the stepping motor driving circuit 311 in accordance with a signal from the control device 310.
[0044]
The output from the CCD image sensor 304 is input to the image processing device 314, and generates a video signal and a luminance signal. This video signal is sent to the storage device 315, and the luminance signal is sent to the control device 310. The control device 310 outputs a signal for driving the stepping motor 11 so that the luminance signal becomes appropriate.
[0045]
FIG. 5 shows a control flowchart of the imaging apparatus of FIG. When the main switch is turned on and the main power supply is turned on, an initialization operation of the light amount adjusting device 1 (aperture / shutter device) is performed (step 401), and the aperture value is changed so as to keep the luminance signal at a predetermined value. (Step 402). Next, if the release SW-S1 is ОN (step 403), a focusing operation is performed (step 404), and the control device 310 calculates an exposure time according to the luminance signal, and drives the shutter according to the calculation result. Data is obtained from shutter data storage means. If the release SW-S1 is $ FF (step 403), the process returns to step 402.
[0046]
If the release SW-S2 is ОN (step 405), a shutter closing operation is performed (step 406), and an image is captured (step 407). If the release SW-S2 is $ FF (step 405), the process returns to step 402.
[0047]
As described above, the imaging device of the present embodiment includes the above-described miniaturized light amount adjusting device 1, so that a miniaturized imaging device can be realized.
[0048]
As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above-described embodiment, the microstep drive is used as the drive method of the stepping motor 11, but a drive method such as two-phase excitation or 1-2-phase excitation may be used.
[0049]
In the above-described embodiment, the inclination of the long holes 144a and 144b is adjusted with respect to the operation direction of the aperture blades 14a and 14b, so that a desired relationship between the rotation angle of the stepping motor 11 and the aperture value can be obtained. Although it is possible to obtain the desired relationship between the rotation angle of the stepping motor 11 and the aperture value, it is possible to adjust the curvature by making the shape of the long hole into an arc shape.
[0050]
【The invention's effect】
As described above, according to the light amount adjusting device according to the first or second aspect, the long holes that engage with the drive pins of the pair of aperture blades are formed obliquely with respect to the operation direction. Since the stroke of the pin can be lengthened, downsizing can be realized.
[0051]
Further, according to the light amount adjusting device according to the third or fourth aspect, since the initialization operation can be performed only by controlling the energization of the stepping motor, it is not necessary to provide the initial position detecting means, and the size can be reduced. be able to.
[0052]
Furthermore, according to the imaging apparatus of the present invention, since the light amount adjusting device having a reduced size is provided, downsizing can be realized.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a configuration of a light amount adjusting device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram illustrating a state of a fully-opened state and a fully-closed state of an aperture of an aperture blade included in the light amount adjusting device illustrated in FIG. 1; FIG. 2A is an explanatory diagram illustrating a state where the opening is fully opened, and FIG. 2B is an explanatory diagram illustrating a state where the opening is fully closed.
FIG. 3 is an explanatory diagram showing a relationship between energized states of two phases, A-phase and B-phase, of a stepping motor included in the light amount adjusting device shown in FIG. 1 and a rotation angle of a blade drive lever.
FIG. 4 is an explanatory diagram illustrating a configuration of an imaging apparatus according to an embodiment of the present invention, which includes the light amount adjustment device illustrated in FIG.
FIG. 5 is a flowchart illustrating a control operation of the imaging device illustrated in FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Light amount adjustment device, 11 ... Stepping motor, 12 ... Blade drive lever, 13a, 13b ... Drive pin, 14a, 14b ... Aperture blade, 144a, 144b ... Long hole, 20 ... Opening, 300 ... Imaging device

Claims (6)

It has a blade drive lever press-fitted to the rotating shaft of the stepping motor, two drive pins protruding from the blade drive lever, and a pair of aperture blades each of which has a long hole engaged with the two drive pins. A light amount adjusting device that adjusts the amount of light passing through the opening by changing the area of an opening formed by linearly reciprocating the pair of diaphragm blades in opposite directions,
The light amount adjusting device according to claim 1, wherein the elongated holes of the pair of aperture blades are formed obliquely to an operation direction of the pair of aperture blades. The light amount adjusting device according to claim 1, wherein the elongated holes of the pair of aperture blades form an angle of 30 degrees or more and less than 90 degrees with respect to the operation direction of the pair of aperture blades. It has a blade drive lever press-fitted to the rotating shaft of the stepping motor, two drive pins protruding from the blade drive lever, and a pair of aperture blades each of which has a long hole engaged with the two drive pins. A light amount adjusting device that adjusts the amount of light passing through the opening by changing the area of an opening formed by linearly reciprocating the pair of diaphragm blades in opposite directions,
Driving the stepping motor from the fully opened state to the fully closed state of the opening with a pulse number equivalent to three pulses in two-phase excitation;
The stepping motor is energized to an energized state corresponding to the first pulse of the two-phase excitation and an energized state corresponding to the second pulse of the two-phase excitation, and then energized to an energized state corresponding to the zeroth pulse of the two-phase excitation. A light amount adjusting device for performing an initializing operation. The initialization operation is performed to change the stepping motor to an energized state corresponding to the second pulse in the two-phase excitation, an energized state corresponding to the first pulse in the two-phase excitation, and an energized state corresponding to the zeroth pulse in the two-phase excitation. 4. The light amount adjusting device according to claim 3, wherein the light amount is adjusted by sequentially applying current. An image pickup apparatus having a light amount adjusting device for adjusting a light amount, wherein the light amount adjusting device includes a blade driving lever press-fitted to a rotating shaft of a stepping motor, and two blade driving levers protruding from the blade driving lever. A drive pin, and a pair of aperture blades each having a long hole engaged with each of the two drive pins, and changing an area of an opening formed by linearly reciprocating the pair of aperture blades in opposite directions. Light amount adjusting device for adjusting the amount of light passing through the opening by
The imaging device according to claim 1, wherein the elongated holes of the pair of aperture blades are formed obliquely with respect to the operation direction of the pair of aperture blades. An image pickup apparatus having a light amount adjusting device for adjusting a light amount, wherein the light amount adjusting device includes a blade driving lever press-fitted to a rotating shaft of a stepping motor, and two blade driving levers protruding from the blade driving lever. A drive pin, and a pair of aperture blades each having a long hole engaged with each of the two drive pins, and changing an area of an opening formed by linearly reciprocating the pair of aperture blades in opposite directions. Light amount adjusting device for adjusting the amount of light passing through the opening by
Driving the stepping motor from the fully opened state to the fully closed state of the opening with a pulse number equivalent to three pulses in two-phase excitation;
The stepping motor is energized to an energized state corresponding to the first pulse of the two-phase excitation and an energized state corresponding to the second pulse of the two-phase excitation, and then energized to an energized state corresponding to the zeroth pulse of the two-phase excitation. An imaging apparatus characterized in that an initialization operation is performed by performing the operation.

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